docs: def preflist_path(self, bucket, key, bucket_type=None, **options):
          """
          Generate the URL for bucket/key preflist information
  
          :param bucket: Name of a Riak bucket
          :type bucket: string
          :param key: Name of a Key
          :type key: string
          :param bucket_type: Optional Riak Bucket Type
          :type bucket_type: None or string
          :rtype URL string
          """
          if not self.riak_kv_wm_preflist:
              raise RiakError("Preflists are unsupported by this Riak node")
          if self.riak_kv_wm_bucket_type and bucket_type:
              return mkpath("/types", quote_plus(bucket_type),
                            "buckets", quote_plus(bucket),
                            "keys", quote_plus(key),
                            "preflist", **options)
          else:
              return mkpath("/buckets", quote_plus(bucket),
                            "keys", quote_plus(key),
                            "preflist", **options)